Owing to the inconvenience and high cost of sending personnel to subscribers' residences in order to collect consumption data for public service utilities, such as water, electricity and gas, it is known to employ electronic metering devices and to collect the data remotely using computerized data-gathering systems. Typically, such computerized data-gathering systems comprise an electronic metering device coupled to a memory which stores a unique access number associated with the electronic metering device together with data corresponding to the consumption of the measured utility.
U.S. Pat. No. 4,652,877 discloses a utility data-gathering system which comprises a standard meter mechanism displaying a digital read-out and coupled to an electronic circuit responsive to the rotation of a shaft within the mechanism so as to convert the mechanical reading to an electronic signal. In such a system, if the electronic circuit becomes inoperative for any reason, such as, for example, a power failure, the mechanism continues to function correctly and the mechanical digital reading provides a back-up of the measured consumption. Utility meters of this kind are commonly used in electronic data-gathering systems with which the present invention is concerned.
U.S. Pat. No. 4,132,981 discloses a system for interrogating and recording a customer's consumption of a utility so as to facilitate automatic invoicing. The system comprises two parts: a computer coupled to an electronic utility meter and a portable interrogation unit including a memory, which is carried by a "meter reader" to each customer location. In response to a suitable interrogation signal, the interrogation unit transmits a signal to the computer which responds by transmitting to the interrogation unit a digital signal corresponding to the utility consumption data stored therein. Such a system permits the meter reader to read the contents of the computer directly so as to record within the interrogation unit the vital statistics of a customer's consumption including, for example, a customer identification number, a meter identification number and a consumption reading.
It is also known for the interrogation unit to include a hand-held computer which is programmed to prepare an invoice automatically which can then be transmitted, via a suitable modem, to a central computer within the utility supply company's billing department.
A drawback with the above system is its inherent lack of flexibility when the meter itself is faulty. It is standard practice to provide with electronic meters some form of integrity check which checks the functionality of the meter. Thus, in the event of a power failure, for example, an error flag is set within the computer which permits ready identification to the meter reader of the fact that the stored reading is inaccurate. Under these circumstances, he must then manually read the mechanical output and enter this into the hand-held computer. Clearly, the electronic reading within the computer must then be updated so as to correlate it with the mechanical reading and this task has hitherto been undertaken by the technical services department of the utility supply company, it having been so far impossible for the meter reader himself to perform this task.
A similar problem occurs when a faulty meter is encountered which needs to be replaced. The meter identification number must be programmed into the computer and, in hitherto proposed systems, the means for doing this have been denied to the meter reader, thereby requiring a separate visit by a member of the technical services department.